1. Field of the Invention
The present invention relates to a blood collection device and, more particularly, to a blood collection device which can not only easily collect blood but also preserve the collected blood fresh for a long period of time, without damaging the blood which is to be analyzed.
2. Description of the Related Art
In recent years, blood-containers made of soft synthetic resin such as soft vinyl chloride resin have come into common use. The use of these containers has rendered component transfusion more common, wherein the blood collected from a donor are divided under aseptic condition into various components such as dense erythrocytes, plasma, platelets, and an anti-hemophilic factor. Component transfusion is applied in order to transfuse to the patient only those components which the patients needs to have, thereby lessening the physical burden on him or her, or thereby to reduce the possibility of immunity-related side effects.
Before applying transfusion to the patient, so-called "cross matching test" is performed in order to determine whether or not the donor's blood matches the patient. This is because, firstly, it is needed to confirm the donor's ABO blood type is the same as that of the patient. Further, even if the donor's blood and the patient's are of the same ABO type, it has to be checked whether aggregation or hemolysis will occur or not due to irregular antibodies contained in the donor's blood or the patient's.
One of the methods of performing cross matching test is to use a blood-collecting tube connected to a needle, as a pilot tube for determining the type of the donor's blood. This method will be described in detail.
In the method, a blood collection device 60 such as the one shown in FIG. 8 is used to collect blood from a donor, and also to separate the blood into components. As is illustrated in FIG. 8, the device 60 comprises a needle 61, a blood-collecting tube 63, a main blood-collecting bag 65, a connecting tube 67, two auxiliary blood-collecting bags 69, 73, and two branching tube 71 and 75, and an erythrocyte-storing bag 77. The needle 61 is attached to one end of the blood-collecting tube 63. The other end of the tube 63 is connected to the main blood-collecting bag 65. The main blood-collecting bag 65 is connected to the second auxiliary blood-collecting bag 69 by means of the connecting tube 67. The tube 67 is connected to the first blood-collecting bag 73 by the branching tube 71, and also to the erythrocyte-storing bag 77 by the branching tube 75.
The erythrocyte-storing bag 77 is filled with normal saline or the like, which has been developed for preserving erythrocytes for a long time and which contains glucose, adenin, and colloid osmoregulator (mannitol).
To collect blood by means of this blood collection device, the needle 61 is inserted into the donor's blood vessel. The blood is collected into the main bag 65 through the needle 61 and the blood-collecting tube 63. The main bag 65 is filled with an anticoagulant solution, known as ACD-A solution or CPD solution, and a medical solution for preserving blood. The blood thus collected is mixed with the medical solutions.
Then, the blood-collecting tube 63 which is connected to the needle 61 is knotted tightly, and is cut from the needle 61. The opening end of the tube 63 is sealed. To prevent the blood remaining in the tube 63 from coagulating, the blood-collecting tube 63 is squeezed and collapsed with a roller pinch or the like, thereby introducing the remaining blood from the tube 63 into the main bag 65. After the collected blood is mixed well with the CPD solution or the like, the roller of the pinch is released, whereby the tube 63 inflates itself due to its elasticity. Then, the mixture of the blood and the medical solutions flows from the main bag 65 into the blood-collecting tube 63.
The blood-solution mixture can be sampled from the main bag 65 in the following another method, so that the collected blood may be analyzed. First, the blood is collected from the donor through the needle 61 and the tube 63 into the main blood-collecting bag 65. Next, the blood is mixed with the anticoagulant solution in the main blood-collecting bag 65. Then, the needle 61 is inserted into the rubber plug of an evacuated blood-sampling tube, whereby the blood is sampled from the tube 63 into the evacuated blood-sampling tube and is subjected to various analyses.
In most cases, the amount of blood sampled into the evacuated blood-sampling tube is much greater than the amount contained in the blood-collecting tube 63, and generally two or more evacuated blood-sampling tubes are used. Every time, a portion of the blood-solution mixture flows into an evacuated blood-sampling tube in the way described above, another equal portion of the blood-solution mixture flows from the main blood-collecting bag 65 into the blood-collecting tube 63. The blood-collecting tube 63 is completely filled with the blood-solution mixture at all times.
The tube 63, always filled up with the blood-solution mixture, is sealed at regular intervals by tube sealers or aluminum rings and cut at the sealed portions. As a result of this, a plurality of pilot tubes, each filled with a portion of the collected blood, generally known as "segmented blood" in the art, which is to be subjected to various analyses.
Identical serial numbers are printed on the blood-collecting tube 63, and at least that end portion of the tube 63 which is connected to the main blood-collecting bag 65 remains, not separated from the main bag 65, it is understood who's blood the pilot tubes contain, in accordance with the serial number printed on the tube 63 connected to the main blood-collecting bag 65.
The main blood-collecting bag 65, now filled with the blood-solution mixture, is put into a centrifugal separator. The separator is driven, until one component of the blood is separated from the remaining components. The main bag 65 is removed from the centrifugal separator, and an upper layer component, thus separated from the others in the main bag 65, is supplied into the first auxiliary blood-collecting bag 73 through the connecting tube 67 and the branching tube 71. Then, the main bag 65 is put into the separator again, and the separator is driven until one of the remaining blood components is separated from the others. The main bag 65 is removed from the separator, and an upper layer component, thus separated from the remaining blood components, is supplied into the second blood-collecting bag 69 through the connecting tube 67.
The dense erythrocytes finally remain in the main blood-collecting bag 65. The erythrocyte-preserving solution contained in the bag 77 is transferred into the main bag 65 through the connecting tube 67 and is mixed with the erythrocyte. In the bag 65, the erythrocytes can thus be preserved for a long period of time.
The blood collection device described above is, however, disadvantageous. When the blood-collecting tube 63 is squeezed and collapsed in preparation for pilot tubes each containing segmented blood, the erythrocytes in the blood are destroyed, causing cythemolysis, which adversely affects the erythrocytes.
In the blood-collecting bag 65, the dense erythrocytes are mixed with the normal saline developed for preserving erythrocytes for a long time and containing glucose, adenin, and colloid osmoregulator (mannitol). Hence, the dense erythrocytes can be preserved for about six weeks.
On the other hand, the erythrocytes in the segmented blood contained in each pilot tube, which is mixed with the ACD-A solution or the CPD solution, can be preserved, but usually for only about three weeks if it is refrigerated. After the three-week period, the segmented blood undergoes cythemolysis, and can no longer be used in cross matching test. Consequently, it impossible to determine, from this segment blood, whether or not the donor's blood matches the patient. To use the segmented blood even after the three-week period, pilot tubes can be made in the following method.
The blood-collecting tube 63 is not sealed and cut right after the blood mixed with the CPD solution and the like has been supplied from the main bag 65 into the tube 63. Rather, erythrocyte-preserving solution is introduced into the main bag 65 and mixed with the erythrocytes therein, and then the blood is made to flow from the tube 63 into the main bag 65 by squeezing and collapsing the tube 63 with a roller pinch. Next, the roller of the pinch is released, making the tube 63 inflate due to its elasticity, and hence allowing the blood-solution mixture to flow from the main bag 65 into the blood-collecting tube 63. Finally, the tube 63, now filled up with the blood-solution mixture, is sealed at regular intervals and cut at the sealed portions, thereby forming pilot tubes, each filled with segmented blood.
In this method, the blood-collecting tube 63 are squeezed twice, inevitably increasing the possibility of cythemolysis and adversely influencing the erythrocytes.
When the blood-collecting tube 63 is squeezed with a roller pinch or the like, the blood contained in the tube 63 and mixed with the CPD solution or the like is replaced by the blood contained in the main bag 65 and mixed with the erythrocyte-preserving solution. The replacement cannot always be performed with high accuracy.